Simplified Freeze-Drying of Mushrooms with Silica Gel

Abstract

As ordinary freeze-drying equipment is rather expensive, experiments were made at the Finnish Forest Research Institute with a simplified method based on the silica gel method developed by Hoseney (1963) at the University of Michigan. Fungi were frozen at -20 C in a household freezer, and kept immersed in silica gel at -20 C until dry. Drying time was 1-3 weeks for small species (Marasmius, Mycena), several months for larger mushrooms, e.g., boletes. A few changes of silica gel were necessary. Fine-grained quality is recommended, as larger crystals tend to wear off gill edges, rings, etc.